Nghe TOEFL

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Listen to part of a lecture in a biology class. The professor is discussing the behavior of honeybees. Professor: Today, I want to talk about how honeybees communicate information about food sources. You might know that honeybees perform a 'waggle dance' to tell other bees where to find nectar. But what’s less known is that the dance’s intensity and duration encode the distance and direction. When a forager returns to the hive, she dances on the vertical surface of the comb. The angle of the dance relative to gravity indicates the angle of the food source relative to the sun. For example, if the dance is straight up, the food is directly toward the sun. If the dance is to the right of vertical, the food is at that same angle to the right of the sun. The duration of the waggle run—the straight part of the dance—correlates with the distance. Longer runs mean farther food. Interestingly, bees can adjust their dance based on the quality of the food. If the nectar is especially sugary, they dance more vigorously, recruiting more foragers. This system is remarkably efficient, allowing the colony to exploit the best resources with minimal wasted effort.